In the construction trades and elsewhere, it has long been desirable to prepare a foamed or nonfoamed sealer which can be applied directly from its container or formed in a simple manner at the application site, for the coating of surfaces, e.g. roofs, to seal the latter against the weather. Heretofore it has been necessary in most cases, to provide upon a roof structure, one or more layers of felt paper and then to coat the surface with a bitumen. Rubber-containing, rubber-like and rubberized compositions have also been proposed as sealants, coating materials and self-supporting sealing layers for these purposes and others. It is desirable in the formation of such layers that the material have a high tenacity, durability, resistance to weathering, flexibility and coating capability in the sense that the material is able to flow naturally over the entire surface, bond thereto and cure to a film or layer free from pinholes or other openings. For the most part, prior-art systems have been unable to fulfill all of these requirements, have been difficult to apply, or have been excessively expensive or supplied in multi-component systems.
I may also mention efforts which have been made to provide compositions of rubber-like materials, such as polyurethanes and bitumens. These efforts have uncovered the phenomenon that bituminous materials react with polyurethane prepolymers to cause premature gelling or partial curing and otherwise detrimentally affect valuable properties which could be derived from the use of polyurethanes. It has been proposed in the art, for example, to negate or obviate such detrimental interaction by reacting the bitumen first with polyurethane prepolymer or isocyanates of the type used in the formation of polyurethanes, but these systems have been only limitedly successful and showed very slow curing.